India declares war on an unwanted urban dweller. The methods may surprise you

Most of the world's big cities face a basic set of problems: traffic, pollution, crime. Then there is Delhi, which has an urban challenge that's nearly unique: too many monkeys. Hungry rhesus macaques roam the streets and even the subway, leap through treetops outside grand government buildings and scale fences around offices and private homes, searching for open windows and accessible food. Even Delhi's police headquarters has been raided by a monkey gang.

To most of the Indian capital's 15 million residents, monkeys are as much a part of the cityscape as Mughal tombs and speeding auto rickshaws. Monkeys and humans have...